从Java字节中提取半字节

Question

Hex:[0A][52][08][01][01][01][00][CD][21][02][59]


0      [0A]
1      [52]         Packettype    = TEMP_HUM
2      [08]         subtype       = TH8 - 
3      [01]         Sequence nbr  = 1
4/5    [01][01]     ID            = 257
6/7    [00][CD]     Temperature   = 20.5 °C
8      [21]         Humidity      = 33
9      [02]         Status        = Dry
10     [5] *nibble           Signal level  = 5
11     [9] *nibble           Battery       = OK

So I get 11 bytes (Hex) in over the serial port. I assigned all the bytes to a byte array so that I can use them later.

I have two qestions:

1] How can I combine the 4 & 5 bytes back together in Java (I am presuming in an INT) ? 2] How can you extract 10 and 11 or the High and Low nibbles of the last byte ?

[FROM COMMENTS BELOW] Example Byte: High[0101][0110]Low lowNibble = yourbyte & 0x0f; 01010110 & 0x0f (00001111) = 00000110

           highNibble = yourByte >>>> 4
           01010110 >>> 4 = 00000101


          IF you use this Example Byte: High[1101][0110]Low
          highNibble = yourByte >>> 4
          11010110 >>> 4 = 00000101
          Because >>> removes the signed bit.

Answer 1

1) It depends on the endianness. It will either be (b[4] << 8) | b[5] (b[4] << 8) | b[5] or (b[5] << 8) | b[4] (b[5] << 8) | b[4]

2) lowNibble = yourByte & 0x0f; highNibble = (yourByte >> 4) & 0x0f; lowNibble = yourByte & 0x0f; highNibble = (yourByte >> 4) & 0x0f;

You can also do: lowNibble = yourByte & 0x0f; highNibble = yourByte >>> 4; lowNibble = yourByte & 0x0f; highNibble = yourByte >>> 4;

The unsigned shift ( >>> ) fills the upper bits with zero, regardless of the sign.